serveRawFs

/@fs/ 相关请求处理

export function serveRawFsMiddleware(): Connect.NextHandleFunction {
  const isWin = os.platform() === 'win32'
  const serveFromRoot = sirv('/', sirvOptions)
  return (req, res, next) => {
    let url = req.url!
    // In some cases (e.g. linked monorepos) files outside of root will
    // reference assets that are also out of served root. In such cases
    // the paths are rewritten to `/@fs/` prefixed paths and must be served by
    // searching based from fs root.
    // 如果 url 以 /@fs/ 为前缀，则视为静态资源获取，
    // 同时，如果是 windows 环境，而且 url 类似于 /@fs/D:asdfasdfasdf 这种带绝对路径的，直接抹除盘符号，强制视为以项目根文件夹为起始路径
    // 通过 sirv 这个库获取静态文件并返回
    if (url.startsWith(FS_PREFIX)) {
      url = url.slice(FS_PREFIX.length)
      if (isWin) url = url.replace(/^[A-Z]:/i, '')
      req.url = url
      serveFromRoot(req, res, next)
    } else {
      next()
    }
  }
}